The present invention relates to an electron beam irradiation apparatus, such as an electron beam exposure apparatus or an electron microscope, and more particularly, it relates to a magnetic shield construction for avoiding magnetic disturbance against the irradiated electron beam.
An electron beam irradiation apparatus is used in a pattern formation process for producing semiconductor devices or in an electron microscope for inspecting the formed patterns of semiconductor devices. A movable stage, such as an XY stage, is installed within a vacuum chamber of the electron beam irradiation apparatus. An electron beam is applied to a specimen placed on a table of the XY stage. An XY stage of high speed and high positioning accuracy is used, especially in the exposure apparatus, for forming the semiconductor patterns. If movable parts of the XY stage are made of a ferromagnetic substance, magnetism from the XY stage changes as the table moves. This causes the path of the electron beam to be deflected, so that a desired pattern cannot be obtained. Making the XY stage a non-ferromagnetic substance involves a great deal of trouble in processing and causes the cost to be high. Even if the XY stage is made of a non-ferromagnetic substance, magnetism from a drive system or other movable parts outside the XY stage affects the electron beam.